"Dennis passed away last night from complications of cardiac arrest," Green's family said in a statement. "His family was by his side and he fought hard."

Green's Vikings made eight playoff appearances in 10 seasons from 1992 to 2001, reaching the NFC Championship Game in 1998 and 2000. He led the Vikings to a 15-1 regular season in 1998 and ranks second in franchise history in games coached, wins and winning percentage, trailing Hall of Fame coach Bud Grant in each category.

"Denny made his mark in ways far beyond being an outstanding football coach," the Vikings said in a statement. "He mentored countless players and served as a father figure for the men he coached. Denny founded the Vikings Community Tuesday Program, a critical initiative that is now implemented across the entire NFL. He took great pride in helping assistant coaches advance their careers. His tenure as one of the first African-American head coaches in both college and the NFL was also transformative."

Mike Tice, who served on Green's staff in Minnesota and succeeded him as head coach, called Green a "great motivator of men."

"Great teacher of coaches. Excellent eye for talent," Tice said. "I hadn't seen Denny in years, but I find myself quoting him: 'Plan your work and work your plan.' He taught me a lot."

Robert Smith, a Fox college football analyst and former Vikings running back, posted his grief over Green's death on Twitter.